Voltage regulator



July 4, 1939. G, TUBES 2,165,080

VOLTAGE REGULATOR Filed NOV. 24, 1937 Fly. 2.

WITNESSES: I INVENTOR Z I F193 A esterGjz/bbs.

Patented July 4, 1939 VOLTAGE REGULATOR Lester G. Tubbl, Wilkinsburg, Pa, assignor to Westinghouse Electric & Manufacturing Com- .pany, East Pittsburgh, Pa., a corporation of Pennsylvania Application November 24, 1937, Serial No. 178,235

Claims.

'My invention relates to regulators and particularly to the control of the primary relay or contact making device that is sensitive to the regulated quantity and controls the operation of the regulator to maintain the regulated quantity, such as voltage, at the desired value.

Voltage sensitive relays for governing the control mechanism of induction regulators are frequently of the alternating-current solenoid type.

The operation of the regulator as controlled by the primary relay determines the voltage of the regulated circuit. The relay core depends upon a constant magnetic field to balance it against gravity. It is desirable to wind the solenoid coil 16 of the relay of copper wire, and since copper has a rather high temperature coefiicient of resistance, the impedance of the coil varies with temperature, requiring a higher voltage to balance the relay at higher coil temperatures than at lower coil temperatures. This causes the relay to so operate as to maintain a higher voltage on the regulated circuit when the primary relay coil is at a high temperature than when it is at a low temperature, thus destroying the accuracy of regulation.

.In the present conventional regulator, the primary relay is compensated to some extent against coil temperature changesby connecting a comparatively high resistance in series with the operating coil. This resistor is made up of material having a very low temperature cceiilcient of resistance so that the eifect of the change in resistance of the operating coil due to changes of temperature thereof is reduced.

The use of the series resistor as above described is objectionable because of the high losses occasioned in the resistor itself, the high voltageampere burden on the circuit, and because it cannot be made effective to completely eliminate the temperature error.

It is an object of my invention to provide means for correcting the temperature error of primary relays or contact making voltmeters.

It is a further object of my invention to pro- 5 vide means for correcting the temperature errors of primary relays in which the losses and voltampere burden are greatly reduced.

Other objects and advantages of my inven tion will be apparent from the following description of one preferred embodiment thereof,

reference being had to the accompanying drawing, in which:

Figure 1 isa tie view illustrating circuits and apparatus comprising a conventional u induction regulator;

circuit represented by conductors l and 2 is illustrated, to which an induction regulator, indicated generally at 3, is provided having a primary or shunt winding 4 and a secondary or series winding 5, the relative positions of which are varied in a well known manner to control the voltage between conductors l and 6 leading to the feeder circuit being regulated. A motor 1 is provided that is connected through suitable operating gearing 8 for operating the shaft 9 to vary the relative positions of the primary and secondary windings l and 5. A transformer 12 is provided having a primary winding l3 connected between the supply conductors i and 2, and a secondary winding ll. One side of the winding H is connected to ground at I5 and the other side is connected by conductor l6 to the movable contact member ll of a' primary relay l8, which upon engagement with the one or the other of the fixed relay contact members I! or 22 closes a circuit extending through con-' ductor 23 or'24 and windings .within the motor 1 to ground at 25, to operate the motor I in the one or the other direction in a well known manner.

The primary relay l8, in addition to the fixed contact members l9 and 22, and the movable contact member i1, includes a movable lever 28 that is pivoted at 21 and carries the contact member IT. The lever 26 is provided at one end with a plunger type core 28 that is free to move within a central opening of a solenoid winding 29, the upward pull of the solenoid 29 opposing the downward pull of gravity on the core 23. A voltage transformer 32 is provided having a primary winding 33 connected between conductors I and 6, and a secondary winding 34 for supplying a voltage to the winding circuit of the primary relay that is a measure of the regulated voltage Er. between conductors I and 5. A resistor 35 is provided in series circuit relation between secondary winding 34 and the solenoid relay winding 29 in the conventional manner as above described.

Referring to Fig.2, the temperature compensating means of this invention includes a reactor 36 in the circuit between the secondary winding 34 of the voltage transformer and the relay op- 5 crating winding 29. A secondary winding 31 that is inductively coupled to the winding 29 may also be provided which may be directly short circuited or short circuited through a resistor 38. The reactor 36 introduces a current component into the primary winding circuit of the relay that is 90 out of phase with the voltage impressed thereon. The core plunger 28 in this case is made of solid soft iron rod instead of being laminated, in order to permit a secondary current therein to establish losses, thereby increasing the flow of current in the circuit of the primary relay winding. In most cases, the losses effective in the core itself will not be sufficient to cause the desired correction, and it then becomes necessary to supply a secondary winding 31, preferably of copper, and short circuited directly or through a resistor 33.

In the vector diagram in Fig. 3, the primary resistance R1 includes the resistance of the reactor coil 36. The PR loss in the iron core 28 of therelay is included in the secondary resistance R2. For the sake of simplicity, the hysteresis and iron losses in the reactor 36, which are small, are neglected.

The following symbols will be used:

Im=exciting current of solenoid (constant). Ez=generated voltage of solenoid (constant). R1=coil resistance including reactor coil. Ra=secondary resistance in terms of main coil. X1=series reactance.

Iz=secondary current in terms of main coil.

I1= 1/ ..+I.= a=angle between-In and I1. Et=applied voltage.

The following solution may be made:

controlling said regulator comprising a soft iron plunger type core and a winding associated therewith, a circuit for said winding, means for impressing a voltage on said circuit that is a measure of the quantity to be regulated, and means for compensating against variations in energization of the primary relay caused by changes in the temperature of the winding comprising a reactor in said winding circuit.

2. In a regulator for governing an alternating current electric circuit, a primary relay responsive to variations in a regulated quantity for controlling said regulator comprising a soft iron plunger type core and a winding associated therewith, a circuit for said winding, means for impressing a voltage on said circuit that is a measure of the quantity to be regulated and means for compensating against varations in the magnetic pull of said winding on said plunger caused by changes in the temperature of the winding comprising a reactor in said winding circuit and a short circuited secondary winding magnetically coupled to said core.

3. In a regulator for governing an alternating current electric circuit, a primary relay responsive to variations in a regulated quantity for controlling said regulator comprising a soft iron plunger type core and a winding associated therewith, a. circuit for said winding and means for impressing a voltage on said circuit that is a measure of the quantity to be regulated, and means for compensating against variations in the magnetic pull of said winding on said plunger caused by changes in the temperature of the winding comprising a reactor in said winding circuit, a secondary winding coupled to said core and a resistor connected thereto.

The following is a typical example: Im=.148 E2=50 R1=90 at C., 109 at 15 C. Ra=600 at 25 C., 725 at 75 C. X1==275 ohms at 60 cycles. I: =.0833 at 25 C., .0688 at 75 C. 11 =.1'I0 at 25 C., .163 at 15 C.

=arc sin .49 at 25 C., .423 at 75 C. =arc cos .8! at 25 C., 91 at 75 C.

sin 0:)

=98.7 volts.

98.6 volts.

It will be noted that in the illustrated example given, the resistance R1 of the operating winding of the primary relay varies from 90 ohms to 109 ohms as the temperature varies from 25 C. to 75 C., while the regulated voltage Er. varies only from 98.? volts to 98.6 volts, or approximately one-tenth of 1%. The regulated voltage, therefore, is substantially unaffected by variations in the temperature of the copper of the primary relay operating winding.

Many changes in the details of the circuits and apparatus illustrated will occur to one skilled in the art within the spirit of my invention, and

I do not wish to be limited otherwise than by thescope of the appended claims.

I claim as my invention:

1. In a regulator for governing an alternating current electric circuit, a primary relay responsive to variations in a regulated quantity for the regulated voltage, and means for compensating said relay for temperaturechanges of the winding comprising a reactor in the winding circult.

5. In combination, a regulator for governing an alternating current electric circuit, means including a primary relay sensitive to the voltage of the regulated circuit for controlling the operation of the regulator, said relay comprising a movable core, a winding for magnetizing said core, a circuit forv energizing said winding, means for applying a voltage to the winding circuit that is a measure of the regulated voltage, and means for eompensatingsaid relay for temperature changes of the winding comprising a reactor in the winding circuit and ashort circuited secondary winding inductively related to said firstnamed windin I 6, In ombination, a regulator for governing an alternating current electric circuit, means inis a measure of the regulated voltage, and means 7 eluding a primary relay sensitive to the voltage for compensating said relay for temperature 7 of the regulated circuit for controlling the op- -changes of the winding comprising a reactor in eration of the regulator, said relay comprising the winding circuit, a secondary winding induc- 5 a movable core, a winding for magnetizing said tively related to the first-named winding and a 5 core, a circuit for energizing said winding, means resistor in circuit therewith. 1 for applying a voltage to the winding circuit that IESTER G. TUBES. 

